There where the Zattere meet the mouth of the rio di San Trovaso, the Ponte Lungo links the two halves of the sunniest promenade in Venice. It is an anomalous bridge for Venetian tradition: low, wide, with a polycentric arch that stretches its back like a ramp instead of rearing it — the form the Austrians gave it in 1836, when they widened the entire shore.